Aspen ===== Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, crusts, drifts, facets, high pressure, natural avalanche, orographic, slabs, stress, sugary, surface hoar, weak layers, wind loading, Mountain Weather and Avalanche Forecast for the Aspen Zone Forecast Issued on 1/25/2008 8:45:57 AM Forecaster: Brian McCall Weather Synopsis High pressure is slowly building into to Colorado as the last system moves eastward. The lower portion of the atmosphere remains quite moist, but there is no real mechanism to wring out precipitation. Clouds and snow showers will continue in areas that produce orographic lifting from southwest and westerly flow. I don't expect more and an inch or two to accumulate. Overnight, wind speeds will continue to increase along the northern portions of the Continental Divide and the Front Range, while mild weather develop in the central and southern mountains. The next storm system is forecast to arrive later on Sunday. Weather forecast models have begun to slow the eastward progression of this system, so we will keep a close eye on the timing over the next few days. Weather Friday Night Saturday Saturday Night Temperature(°F) 14-19 2-7 18-23 Wind Speed(mph) 15-25 G35 15-25 G35 15-25 Wind Direction W W WSW Sky Cover Mostly Cloudy Mostly Cloudy Decreasing Snow(in) 2-5 0-2 0-1 Snowpack Discussion Weather stations are showing 3-6" of new snow around the Aspen Zone overnight. The Schofield area looks to have picked up a little more with 8-10" falling there. This storm has not been a big snow producer for the area but wind speeds during the day yesterday and overnight were high enough to transport snow onto lee aspects. S and SW winds blew all day yesterday and loaded slopes facing N-NE-E. Overnight they have switched to a more westerly direction. This wind loading created one small natural avalanche on an E aspect above treeline near the Peter Estin hut. Although it was small, this avalanche is a good indication of some of the tender wind slabs you will find in the backcountry today. Look for some fresh wind drifts on slopes facing N-NE-E-SE, near and above treeline, as you venture out. New storm snow and wind deposited snow will be stressing a couple weak layers in the upper snowpack. Layers of "sugary" facets, feathery surface hoar grains in some areas, and some slick crusts are all getting buried by this new snow. Look for these weaknesses in the upper 1-2 feet of the snowpack. Near and below treeline, a layer of surface hoar buried just over a week ago on SE-S-SW aspects may also start to become a problem. Watch for avalanche activity on this layer, especially in steeper pockets below treeline. Most avalanches that occur today will happen in these upper snowpack weak layers. However..... We cannot have a snowpack discussion this winter without mentioning those persistent, deep weak layers. Although they are becoming difficult to trigger, avalanches do have the potential to step down and become large events. The structure of the snowpack right now inspires VERY LITTLE confidence for bigger terrain in most areas of the Aspen Zone. A stronger layer in the middle of the snowpack may give you a false sense of security but remember that our snow cover in Colorado is highly variable. Find an area where that midpack is thinner and you may find yourself going for an unplanned ride. Avalanches in these conditions are often triggered from lower on the slope where the snowpack thins out and puts you closer to those weak layers. Avalanche Danger With new snow and recent wind loading, we will hold the danger at CONSIDERABLE on north, northeast, east, and southeast aspects near and above treeline. Winds out of the S-SW-W have created some fresh slabs on these easterly aspects. The avalanche danger on all other aspects near and above treeline and all slopes below treeline is rated MODERATE. You need to choose your terrain wisely. Good route finding and the ability to select terrain that is appropriate for the current conditions are two great tools to take with you into the backcountry this season. There is a lot of great riding out there now, but the snowpack demands a lot of respect. Consider the consequences of a wrong decision. The CAIC Aspen office needs your backcountry avalanche, weather, or snowpack observations. These are a great help to our forecasters. Please drop us an e-mail at caic@qwest.net with anything you are seeing out there today. Front Range =========== Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, high pressure, human triggered avalanches, natural, orographic, slab, whumpfing, wind slabs, Mountain Weather and Avalanche Forecast for the Front Range Zone Forecast Issued on 1/25/2008 8:02:52 AM Forecaster: Ethan Greene Weather Synopsis High pressure is slowly building into to Colorado as the last system moves eastward. The lower portion of the atmosphere remains quite moist, but there is no real mechanism to wring out precipitation. Clouds and snow showers will continue in areas that produce orographic lifting from southwest and westerly flow. I don't expect more and an inch or two to accumulate. Overnight, wind speeds will continue to increase along the northern portions of the Continental Divide and the Front Range, while mild weather develop in the central and southern mountains. The next storm system is forecast to arrive later on Sunday. Weather forecast models have begun to slow the eastward progression of this system, so we will keep a close eye on the timing over the next few days. Weather Friday Night Saturday Saturday Night Temperature(°F) 18-23 1-6 18-23 Wind Speed(mph) 20-30 G40 25-35 G50 25-35 G60 Wind Direction WSW W W Sky Cover Mostly Cloudy Mostly Cloudy Decreasing Snow(in) 1-3 0-2 0 Snowpack Discussion Thursday was a beautiful day in the Front Range zone with sunny skies and moderate winds. It even felt a little warm. No new avalanche activity has been reported since Wednesday. However, the most recent reports are not that encouraging as they include a large natural from the Berthod Pass area (SE, 11,700, 3 feet deep and 400 feet wide) and a avalanche in the low-elevation areas of Willow Creek Pass. I don't expect too much new snow to fall in the Front Range zone over the next few days, but we are going to get some strong winds. As the winds load easterly slopes, watch for signs of increasing instability such as cracking in the surface snow and whumpfing sounds. Of course if you see a fresh avalanche that means slopes with a similar aspect, elevation and slope angle could be dangerous. Recent weather conditions including cold temperatures and periods of strong winds have done little to change the concern for deep slab instabilities. If you trigger an avalanche in the surface layers, it could break down into the weaker basal layers creating a large and dangerous avalanche. You might also trigger a deep-slab avalanche from an area where the snowpack is not very deep. Think about the consequences of getting caught in an avalanche as you choose your route. Watch your slopes angles and have an escape route planned in case the worst happens. Avalanche Danger The avalanche danger is CONSIDERABLE on northeast, east, southeast, and south aspects near and above treeline. Upper snowpack slides involving reactive wind slabs and deep slab instabilities are the two concerns. Human triggered avalanches are probable in these areas. Elsewhere and below treeline the danger is MODERATE. Grand Mesa ========== Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, high pressure, human triggered avalanches, orographic, wind loaded, wind-loaded, Mountain Weather and Avalanche Forecast for the Grand Mesa Zone Forecast Issued on 1/25/2008 9:36:13 AM Forecaster: Ethan Greene Weather Synopsis High pressure is slowly building into to Colorado as the last system moves eastward. The lower portion of the atmosphere remains quite moist, but there is no real mechanism to wring out precipitation. Clouds and snow showers will continue in areas that produce orographic lifting from southwest and westerly flow. I don't expect more and an inch or two to accumulate. Overnight, wind speeds will continue to increase along the northern portions of the Continental Divide and the Front Range, while mild weather develop in the central and southern mountains. The next storm system is forecast to arrive later on Sunday. Weather forecast models have begun to slow the eastward progression of this system, so we will keep a close eye on the timing over the next few days. Weather Friday Night Saturday Saturday Night Temperature(°F) 20-25 5-10 24-29 Wind Speed(mph) 10-20 5-15 5-15 Wind Direction WSW SW SW Sky Cover Mostly Cloudy Mostly Cloudy Decreasing Snow(in) 2-4 0-2 0-1 Snowpack Discussion There have been 11 inches of new snow on Grand Mesa in the last 24 hours. The new snow fell onto some very weak snow and has increased the avalanche danger. Human triggered avalanches are probable on steep wind loaded slopes. On slopes that were not affected by the wind, human triggered avalanches are still possible. Slopes steeper than about 35 degrees are the most dangerous, so watch you slope angles. Be sure to cross open slopes one at a time and don't expose more than one person to a potential avalanche. Conditions will be changing during the day to make sure to evaluate each slope before you move out into open areas. Avalanche Danger The avalanche danger for the Grand Mesa zone is CONSIDERABLE on north, northeast, east, southeast, and south aspects near and above treeline. Human triggered avalanches are possible, especially on wind-loaded slopes 35 degrees and steeper. The danger is MODERATE on other near and above treeline aspects and all aspects below treeline. Please send observations from this or any other zone to [57]caic@qwest.net San Juan North ============== Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, high pressure, orographic, weak layers, wind slabs, Mountain Weather and Avalanche Forecast for the Northern San Juan Mountain Zone Forecast Issued on 1/25/2008 8:03:44 AM Forecaster: Ethan Greene Weather Synopsis High pressure is slowly building into to Colorado as the last system moves eastward. The lower portion of the atmosphere remains quite moist, but there is no real mechanism to wring out precipitation. Clouds and snow showers will continue in areas that produce orographic lifting from southwest and westerly flow. I don't expect more and an inch or two to accumulate. Overnight, wind speeds will continue to increase along the northern portions of the Continental Divide and the Front Range, while mild weather develop in the central and southern mountains. The next storm system is forecast to arrive later on Sunday. Weather forecast models have begun to slow the eastward progression of this system, so we will keep a close eye on the timing over the next few days. Weather Friday Night Saturday Saturday Night Temperature(°F) 17-22 -1-4 18-23 Wind Speed(mph) 10-20 5-15 5-15 Wind Direction SW SSW SSW Sky Cover Mostly Cloudy Mostly Cloudy Decreasing Snow(in) 1-4 0-1 0 Snowpack Discussion New snow totals in the Northern San Juans are in the 3-6 inch range, expect on Molas and Coal Back passes where about a foot of new snow fell overnight. The winds have generally been from the southwest and quite strong along exposed ridgelines. Overnight wind speeds were in the 25-35 mph range with gusts into the 40's and 50's. Reports from the NSJ indicate that the below treeline snowpack is gaining strength. However, as you approach and move above treeline there are still some nasty weak layers buried under wind slabs. Recent snow and wind will increase the load on these layers making them more reactive today. The near and above treeline areas remain a bit like a mine field, with fairly unstable areas scattered within larger areas of stability. Today is a good day to get out and look at the distribution of the new snow. Managing the terrain will be key, so watch your slope angles and evaluate each open slope before you venture out of a protected area. The most recent avalanche activity has been on N, NE and W facing slopes, above 12,000 feet and on slopes steeper than about 35 degrees. Avalanche Danger The avalanche danger in the Northern San Juan zone is CONSIDERABLE in near and above treeline areas on all aspects. Below treeline, the danger is generally MODERATE. San Juan South ============== Current Keywords: CONSIDERABLE, avalanche danger, high pressure, human triggered, natural, orographic, slab, Mountain Weather and Avalanche Forecast for the Southern San Juan Mountain Zone Forecast Issued on 1/25/2008 8:03:50 AM Forecaster: Ethan Greene Weather Synopsis High pressure is slowly building into to Colorado as the last system moves eastward. The lower portion of the atmosphere remains quite moist, but there is no real mechanism to wring out precipitation. Clouds and snow showers will continue in areas that produce orographic lifting from southwest and westerly flow. I don't expect more and an inch or two to accumulate. Overnight, wind speeds will continue to increase along the northern portions of the Continental Divide and the Front Range, while mild weather develop in the central and southern mountains. The next storm system is forecast to arrive later on Sunday. Weather forecast models have begun to slow the eastward progression of this system, so we will keep a close eye on the timing over the next few days. Weather Friday Night Saturday Saturday Night Temperature(°F) 20-25 6-11 25-30 Wind Speed(mph) 10-20 G30 5-15 G25 10-20 Wind Direction WSW SW SW Sky Cover Mostly Cloudy Mostly Cloudy Decreasing Snow(in) 1-4 0-1 0 Snowpack Discussion There has been more than a foot of new snow in the Southern San Juan zone in the last 24 hours. Winds have generally been from the southwest in the 10-15 mph range with gusts in the 30's and 40's.The winds were a bit stronger on the western side of the zone. There have been relatively few new avalanches reported from the Southern San Juan, but with a foot of new snow and wind, today could be different. Yesterday, observers described lots of cracking and fairly reactive new snow layers, and you are likely to find similar conditions today. New snow avalanches could be 1-2 feet deep, which is certainly big enough to get you into trouble. Watch your slope angles and travel one at a time across open slopes. The snowfall will decrease during the day, but there will be enough wind to transport the new snow on to lee slopes. Avalanche Danger The avalanche danger for the southern San Juan zone is CONSIDERABLE. Fresh snowfall will make human triggered soft slab slides probable and natural slides possible on all steep slopes. Sangre de Christo ================= Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, cross loaded, high pressure, human triggered, lee , orographic, slab, slabs, wind loaded, wind slabs, Mountain Weather and Avalanche Forecast for the Sangre De Cristo Zone Forecast Issued on 1/25/2008 8:03:56 AM Forecaster: Ethan Greene Weather Synopsis High pressure is slowly building into to Colorado as the last system moves eastward. The lower portion of the atmosphere remains quite moist, but there is no real mechanism to wring out precipitation. Clouds and snow showers will continue in areas that produce orographic lifting from southwest and westerly flow. I don't expect more and an inch or two to accumulate. Overnight, wind speeds will continue to increase along the northern portions of the Continental Divide and the Front Range, while mild weather develop in the central and southern mountains. The next storm system is forecast to arrive later on Sunday. Weather forecast models have begun to slow the eastward progression of this system, so we will keep a close eye on the timing over the next few days. Weather Friday Night Saturday Saturday Night Temperature(°F) 18-23 7-12 21-26 Wind Speed(mph) 11-21 15-25 19-29 Wind Direction W W W Sky Cover Mostly Cloudy Mostly Cloudy Partly Cloudy Snow(in) 0-2 0 0 Snowpack Discussion Our last observation from the Colorado Sangres nearly two weeks ago noted plenty of hard slabs to be found. These were primarily on the lee aspects due to persistent northerly winds, but could be found on cross loaded terrain features like gullies as well. The Sangres have a relatively shallow snowpack. The primary concern in neighboring zones with shallow snowpacks is localized deep slab instabilities. The stiff wind slabs will hold your weight in many areas, but you can breakthrough weak spots especially near cliffs, rock outcroppings and vegetation. If you do trigger a slide from a weak spot, it could cause the entire snowpack to slide creating a large avalanche. As you travel, constantly reevaluate the snowpack for signs of these instabilities. Think of the consequences of a big ride during your route selection process. As always, we really like to get observations, even if it is just cloud cover and new snow from the valley floors. Avalanche Danger The avalanche danger in the Sangre de Cristo Zone is CONSIDERABLE near and above treeline on NE-E-SE-SW aspects and MODERATE near and below treeline on the other aspects, W-NW-N. Human triggered slides are possible to probable today. Carefully evaluate steep wind loaded slopes. Please send observations from this or any other zone to [57]caic@qwest.net Sawatch ======= Current Keywords: CONSIDERABLE, LOW, MODERATE, avalanche danger, cross loading, cross-loaded, front, high pressure, human triggered, orographic, powder , slab, slabby, slabs, weak layers, wind loaded, wind slabs, Mountain Weather and Avalanche Forecast for the Sawatch Range Zone Forecast Issued on 1/25/2008 8:44:51 AM Forecaster: Brad Sawtell Weather Synopsis High pressure is slowly building into to Colorado as the last system moves eastward. The lower portion of the atmosphere remains quite moist, but there is no real mechanism to wring out precipitation. Clouds and snow showers will continue in areas that produce orographic lifting from southwest and westerly flow. I don't expect more and an inch or two to accumulate. Overnight, wind speeds will continue to increase along the northern portions of the Continental Divide and the Front Range, while mild weather develop in the central and southern mountains. The next storm system is forecast to arrive later on Sunday. Weather forecast models have begun to slow the eastward progression of this system, so we will keep a close eye on the timing over the next few days. Weather Friday Night Saturday Saturday Night Temperature(°F) 12-17 5-10 18-23 Wind Speed(mph) 15-25 15-25 15-25 Wind Direction WNW W W Sky Cover Mostly Cloudy Mostly Cloudy Decreasing Snow(in) 2-4 0-2 0 Snowpack Discussion New snow along the zone range from 3 to 7 inches. It seems that the Cottonwood Pass area has done better than we thought from this storm system. Ridge top winds have been breezy moving new snow to above tree line slopes facing east and cross loading ones facing north east and south east. Expect to find tender slabs in these areas. Although we have not received any new reports of avalanche activity this week, we know they have occurred as the snowpack throughout the zone does not instill much confidence for being stable. With the continued cold temperatures, a general weakening of the old snow will continue. Any new snow, and wind deposited snow will have weak layers to rest on. We are anticipating the complex snowpack structure will result in variable unstable layers for well into the spring. The forecast is for several more inches of new snow accompanied by moderate to strong winds. This will put yet another layer of slabby snow on top of a collection of older wind slabs and persistently weak layers. Human triggered slides in the surface slabs will be possible to probable on steep slopes. Localized deep slab instabilities are still lurking. These deeper weak layers are here to stay and should be on the forefront of your decision making process. If you trigger a smaller slide, it could step down into the snowpack to create a much deeper and larger avalanche. Finding a thin spot in the hard slab may also trigger a large slide. You can find buried thin hard slabs near rock outcroppings, downed timber, and BELOW cliff bands. Be particularly aware of potential consequences of triggering a deep avalanche. Avoid steep slopes that if they avalanche they could carry you over cliff bands or into trees. Choose your terrain wisely by knowing where you are, measuring slope angles and having your escape routes planned. With the new snow do not forget to temper your powder fever. It is hard to do this but give the snowpack time to adjust to the new load before diving in. Stick to slopes less than 34 degrees for a few days and evaluate each slope individually. Lots of excellent riding conditions can be found out there but the current snowpack structure demands a lot of respect. Avalanche Danger The avalanche danger in the Sawatch Zone includes pockets of CONSIDERABLE on steep wind loaded and cross-loaded slopes on northeast, through southeast and south aspects near and above treeline. On other aspects near and above treeline the danger is MODERATE. Below treeline, the danger is LOW on all aspects. [57]Please let us know if you see any avalanche activity or experienced signs of instability. Steamboat ========= Current Keywords: LOW, MODERATE, avalanche danger, cross-loaded, depth hoar, high pressure, orographic, wind slabs, Mountain Weather and Avalanche Forecast for the Steamboat and Parks Range Zone Forecast Issued on 1/25/2008 8:02:39 AM Forecaster: Ethan Greene Weather Synopsis High pressure is slowly building into to Colorado as the last system moves eastward. The lower portion of the atmosphere remains quite moist, but there is no real mechanism to wring out precipitation. Clouds and snow showers will continue in areas that produce orographic lifting from southwest and westerly flow. I don't expect more and an inch or two to accumulate. Overnight, wind speeds will continue to increase along the northern portions of the Continental Divide and the Front Range, while mild weather develop in the central and southern mountains. The next storm system is forecast to arrive later on Sunday. Weather forecast models have begun to slow the eastward progression of this system, so we will keep a close eye on the timing over the next few days. Weather Friday Night Saturday Saturday Night Temperature(°F) 20-25 5-10 23-28 Wind Speed(mph) 15-25 G35 15-25 G35 10-20 G30 Wind Direction WSW WSW WSW Sky Cover Mostly Cloudy Mostly Cloudy Decreasing Snow(in) 2-4 1-4 0-1 Snowpack Discussion The snowy streak in the Steamboat zone continues with 1-3 inches of new snow overnight. More snow will fall today, but I don't expect a huge dump. The Steamboat area was plagued with a depth hoar snowpack early in the season, but an extended period of snow fall has helped form a stronger snowpack. Although the stability across the snow has improved, you still might be able to find some of that old weak snow on shady slopes with a thin snowpack. A bigger concern for today are the recent snow layers. The winds have been from the westside of the compass, so look for wind slabs on NE-E-SE facing slopes. Watch for cross-loaded slopes and slowly work your way into steeper terrain. Avalanche Danger The avalanche danger in the Steamboat Zone is MODERATE near and above treeline. Well below treeline, the danger is LOW. If you have any observations or data to share, please send them to [57]caic@qwest.net. Vail ==== Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, cross loaded, faceting, facets, high pressure, human triggered, human triggered avalanches, orographic, slab, slabs, start zones, weak layers, wind slab, wind slabs, Mountain Weather and Avalanche Forecast for the Vail and Summit County Zone Forecast Issued on 1/25/2008 8:44:42 AM Forecaster: Brad Sawtell Weather Synopsis High pressure is slowly building into to Colorado as the last system moves eastward. The lower portion of the atmosphere remains quite moist, but there is no real mechanism to wring out precipitation. Clouds and snow showers will continue in areas that produce orographic lifting from southwest and westerly flow. I don't expect more and an inch or two to accumulate. Overnight, wind speeds will continue to increase along the northern portions of the Continental Divide and the Front Range, while mild weather develop in the central and southern mountains. The next storm system is forecast to arrive later on Sunday. Weather forecast models have begun to slow the eastward progression of this system, so we will keep a close eye on the timing over the next few days. Weather Friday Night Saturday Saturday Night Temperature(°F) 18-23 2-7 19-24 Wind Speed(mph) 15-25 G40 20-30 10-20 G30 Wind Direction WSW WSW WSW Sky Cover Mostly Cloudy Mostly Cloudy Decreasing Snow(in) 1-3 0-1 0 Snowpack Discussion Yesterday, touring in the North Fork of the Swan River area, I observed signs of several slab avalanches that probably occurred earlier in the week. All occurred above tree line on east through south aspects. Performing stability test did not instill much confidence in our snowpack. Also on Thursday, avalanche mitigation work near Vail Pass produced a number of small soft slabs on southwest through northwest facing aspects. More wind and some light snow in the forecast could add yet another layer of storm snow and wind slab on top of the existing hard and weak layers. Human triggered soft slabs failing from beneath the recent storm snow and wind slabs are possible to probable. We have not received a "dump" in quite some time, but some locations in the zone have received close to a foot of new snow in the past week; inch by inch. The backcountry does not indicate this much snowfall so it has been redistributed, forming slabs that are sitting above weak surface facets. Surface layers in cross loaded start zones facing north, east and south have been the most reactive. The cold temperatures this month have really driven the surface faceting process making shallow slab stability poor. If you trigger one of these soft slabs, the probability of the fracture stepping down to deeper weak instabilities is of greater concern. Finding a thin spot in the hard slab may also trigger a larger and deeper avalanche. Thinner hard slabs can be found near rock outcroppings, downed timber and BELOW cliff bands. Before riding any slope, think of the consequences if you were to trigger a large avalanche. Avoid steep slopes above cliff bands or steep trees as being carried through them by an avalanche would really hurt. The structure of our snow pack instills very little confidence for riding bigger terrain through out the zone. Choose your terrain wisely by knowing where you are, measuring slope angles and having your escape routes planned. The name of the game with our current snowpack is avoiding start zones steeper than 34 degrees as well as terrain features that terminate in a creek bottom or abruptly. Lots of excellent riding conditions can be found out there but the current snowpack structure demands a lot of respect. We all know of sweet big dogs but when they bite, they bite hard! Avalanche Danger The avalanche danger in the Vail-Summit Zone is MODERATE with pockets of CONSIDERABLE on slopes steeper than 34 degrees that have been wind loaded or cross loaded facing north, through east, south, and southwest aspects near and above treeline. Human triggered avalanches are probable in these areas. Elsewhere the danger is MODERATE.